Rail bond tester



Sept. 15, 1931. F. w. ROLL ER ,471

RAIL BOND TESTER Filed March 8, 1926' 2 Sheets-Sheet l Sept. 15, 1931. F. w. I-ROLLER 1,823,471

RAIL BOND TESTER Filed March a, 1925 2 Shets-Sheot 2 is N $3 ance/"tom Eula/0 WZZoZZer 2M 2 Ragw- -E W,

Patented Sept. 15, 1931 UNITED, STATES,

PATENT OFFICE FRANK W. ROLLER, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO ROLLER-SMITH COMPANY, A CORPORATION OF NEW YORK RAIL BOND TESTER Application filedMarch s, 1926. Serial No. 93,039.

This invention relates to rail bond testers which include electric testing instruments, the circuits of which are energized by current derived from the rail through'rail engaging contacts carried by a contact bar or similar device. 1

When the rails are normally carrying current as from carsoperating on track, this current may be utilized for energizing the testing circuits and making the tests. This, however, is impossible if the rails do not happen to be carrying current at the time it is desired to make the test and one object of the present invention is to provide a convenient means for establishing a flow of current through the rails in such cases. For this purpose, I provide additional rail engaging contacts on the contact bar, a suitable source of current such as a small battery or dry cell carried by the contact bar and connections between said source and contacts, the parts being so arranged that when the contact bar ispressed against the rail so as to connect the testing circuits with the rail, the additional contacts also engage the rail so that current from the source will be supplied to the rail; this current being utilized to energize the circuits of the testing apparatus. To avoid closing the circuit through the battery at the times when the rails are carrying current, and current from the battery is, therefore, unnecessary, I provide a switch in. the connections between the source and additional contacts, and in the preferred embodiment of my invention, this switch is normally open, and may or may not be closed by the operators foot in pressing the contact bar againstthe rail.

A further object in my invention is to provide an improved contact bar embodying the instrumentalities above mentioned whichbar is of simple and light ,constructiomis collapsible so as to facilitate carrying, and which, at the same time, is strong and durable andefiicient in use.

A further object of my invention is to provide improved rail-engaging contacts which are so constructed and mounted as to insure engagement of all of the contacts with the rail when the contact bar is pressed against the rail, so that, a good electrical connection is torlmed between each of the contacts and the ram Further objects and advantages of my invention will appear from the following description taken in connection with the accompanying drawings, wherein Fig. 1 is a side elevation of a rail and contact bar applied thereto, together with a conventional showing of the electrical circuits of the testing apparatus including a testing rheostat and galvanometer; Fig. 2 is a sectional view taken on the line 2-2 of Fig. 1; Fig. 3 is a side elevation of the contact bar folded; Fig. 4 is an enlarged View of one end of the contact part partly in longitudinal section and partly in elevation showing in detail two of the rail engaging contacts; and Fig.5 is. an enlarged elevation of one end of the contact bar.

Referring to Fig. 1, 10 and 11 represent two track rails joined together by a rail bond 12. 14 represents a contact bar which comprises a handle 15 to the lower end of which are secured plates 16 between which are pivoted members 19 and 20, which in their operative or rail engaging position extend outwardly from the handle 15 and are held in such posi tion by braces 23 and 24L Thesebraces are pivotally secured at one end to the handle 15,and are detachably secured at the other end to the members 19 and 20 respectively. lVhenthe braces are detached from the parts 19 and 20, these parts may be folded up against the handle as shown in Fig. 3 for convenient carrying ot'the bar when not in use. In the embodiment of the invention herein disclosed, the contact bar carries three rail engaging contacts, namely, contacts 25 and 26 carried by the parts 19 and 20, respectively, and contact 27 carried by the lower end of the handle 15; these three contacts forming parts of the testing circuits; and the contact bar also carries two additional contacts 28 and 29 located respectively at the outer ends of the parts 19 and 20, these additional contacts forming part of the circuit for supplying current to the rail.

Contacts 25, 26 and 27 are of similar form and each is rigidly secured to the part of the p 3 60 on the resistance54. The contact arin60 bar on which it is mounted. Figs. 4 and 5 show the form of one of these contacts, namely contact on part 19. It comprises a metal body portion 30, which embraces and is suitably secured to the part 19 of the contact bar andv which is formed with downwardly inclined arms 31 having slots 32 adapted to receive rail engaging members 33, which, in the preferred construction are sections of a hack-saw. Members 33 are removably held in the slots 32 by screws 35 and members 33 are so positioned that when the contact bar is pressed downwardly against the rail, the saw teeth engage two top edges of the rail, and serve to penetrate any scale or non-conducting coating on the surface of the rail and form a good electrical contact with the metal of the rail. Fig. 2 shows the center contact 27 engaging the rail in this manner. The body portion 30 of the contact carries a binding post 36 for connection thereto of a conducting lead. i

j Contacts 28 and 29 have railengaging saw blades carried bydownwardly inclined arms 37of a body portion 38, and the saw blades arepositioned relatively to one another similarly to the saw blades on the contacts 25, .26 and 27. Contacts 28 and 29 are supported so, that they may yield relatively to the parts 19 and 20 respectively. The mounting of the contact 28 is shown in Fig. 4. A spring 40 carried in a tube 41 in part 19 presses against the upper end of the body portion 38 normally holding the body portion 38 against a supporting bracket 42, which is secured to the part 19 and extends beneath the bodyportion 38 between the projecting arms 37.; When the contact bar 14 is pressed against the rail and the saw, teeth ofthe contacts 28 and '29 engage the top edges of the rail, and the yieldable connectionsbetween these contacts and part 19 and 20 permit the bar to move toward the rail until contacts 25,. 26 and 27 come into firm engagement with the rail. Inasmuch as contacts, 25,

26 and 27 are spaced some distanceapart and the contact bar itself is somewhat resilient, apressure applied to the part 19 or 20 of the bar somewhat near their connection with the handle will force all three contacts, 25, 26 and 27 into engagement with the rail.

represents a 'portable box or case which contains a rheostat 51 and a galvanometer 52 The rheostat 51 comprises a resistance 54, one terminal 55 of which is connected to thecontact26 by flexible conductor 56 and the otherterminal 57 of which is connected to so as to form contact with the resistance 54 at any point along its-length, and apo-inter62 movable with the arm cooperates with a dial 63 toindicate the position of the arm is connected through a galvanometer 52 to the center contact 27 of the contact bar by means of a flexible conductor 65. j

represents a battery or dry cell which is carried in any convenient manner by the handle 15 of the contact bar. As shown, the battery 7 0 is supported by a bracket 71 secured to the handle 15 and a strap 72 which encircles the battery and handle, holds the latter firmly against the handle. One terminal of the battery is connected by means of a conductor 74 to the contact 29 and the remaining terminal of the battery leads through a conductor 76 to a push switch 75,

mounted in the part 19 of the contact bar. A

conductor 77 leads from the rail engaging contact 28 to the push switch 75, andconductors 6 and 77 are adapted to vbe electrically connected by a movable switch contact member 79, which is normally held in an upper or circuit open position by a spring 80 contained in a tube 81 in the part 19 and engaging a collar 82 formed on the contact member 79. Contact member 79 extends upwardly a slight distance above the top of the part 19 where it may be engagedby the foot of the operator in pressing the contact bar against the rails.

To test the rail bond by the apparatus described, the bar is placed along the rail so that contacts 26 and 27 are at'opposite sides of the bond to be tested. 'As it is unneces sary to use the battery current when the rails are already carrying current, the bar will be first pressed against the rails in such a manner as not to close the switch 7 5 This may be done by pressing the foot against the inner end of the part 20 of the contact bar, and in case current is flowing through the rails this will be indicated by a movement by the galvanometer needle. If the galvanometer does not indicate a flow of current through the rails, the operator will place his foot over. the switch 75 and press the bar against the rails thereby simultaneously closing the pressedagainst the rails as above described and the galvanometer has indicated a current flow throughthe rails, the arm 60 will be adjusted along the resistance 54 until the galvanometer gives a zero deflection. The circuits now established form a VVheatstone bridge with the resistances of the arms ot'the bridge so adjusted that no current is flowing throughthe bridge circuit. The arms of the bridge at one end of the bridge-or galvanometer circuit are the resistance of the rail bond 12, and the resistance of a length of track equal to the distance'between the contacts 25 and 27. The other two arms of the bridge are formed by the portions of the resistance 54 at opposite sides of the arm 60.

If the ratio of the resistances of these two port-ions of the resistance 5a are known, the resistance of the bond 12 in terms of the resistance ofthe standard length of rail, that is, the length equal to the distance between the contacts 25 and 27 may be ascertained. Dial 63 will ordinarily be graduated, to read directly in ratioof bondresistance to resistance oi standard length of rail.

Although one specific embodiment of my invention has beenshown and described, various modifications may be made without departing from the scope of this invention.

I claim:

1. In an apparatus for testing the electric resistance of rail bonds, a contact bar arranged to be held pressed against the rail by foot pressure, an electrical measuring instrument, a pair of spaced testing contact members disposed on said bar so as to be brought into engagement with the rail on application'or' foot pressure to said bar, circuit connections between said testing instrument and said testing contact members whereby upon application of foot pressure to said bar, said testing contact members will be brought into engagement with said rail and cause rail return current flowing though said rail to produce on said instrument an indication of the resistance of a tested rail'section between said testing contact members, a pair of auxiliary contact members disposed on said bar outside said spaced testing contact members, an auxiliary current source associated with said apparatus, a normally open switch disposed on said bar arranged to be closed upon application of foot pressure to a predetermined portion oif said bar, and connections between said auxiliary contact members, said auxiliary source, and said switcharranged so that upon application of foot pressure to said predetermined portion of said bar, said testing and auxiliary contact members will be brought into engagement with said rail and simultaneously said switch will be closed, causing a flow of current from said auxiliary source through said rail to produce on said instrument an indication of the resistance of the aforesaid tested rail section in the same terms as when actuating said instrument with rail return current. a

2. In an apparatus for testing the electric resistance of rail bonds, a contact bar arranged to be held pressed against the rail by foot pressure, an electrical measuring instrument, a pair of spaced testing contact members disposed on said bar so as to be brought into engagement with the rail on application of foot pressure to said bar, circuit connections between said testing instrument and said testing contact members whereby, upon application of foot pressure to said bar, said testing contact members will be brought into engagement with said rail and cause rail returnv current flowing through said rail to pro"- duceon said instrument an indication of the resistance of a tested rail section between said testing contact members,.a pair of auxiliary contact members disposed on said bar outside said spaced testing contact members, an auxiliary current source associated wi h said apparatus, a normally open switch disposed on said bar arranged to be closed upon application of foot pressure to a predetermined portion of said bar, and connections between said auxiliary contact members, said auxiliary source, and said switch arranged so that upon application of foot pressure to said predetermined portion of said bar, said testing and auxiliary contact members will be brought into engagement with said rail and simultaneously said switch will be closed, causing a flow of current from said auxiliary source through said rail to produce on said instrument an indication of the resistance of the aforesaid tested rail section in the same terms as when actuating said instrument with rail return cin'rent, said auxiliary contact members being relatively yieldably mounted on said bar compared to said testing contact members so that upon application of foot pressure to said bar, said auxiliary contact members will yield until said testing contact members have been brought into engagement with the rail to be tested.

3. An apparatus for testing the electrical resistance of rail bonds, a contact bar adapted to be held pressed against the rail by foot pressure, an electrical measuring instrument,

a pair of outer testing contact members and an intermediate testing contact member disposed on said bar so as to be brought into engagement with the rail upon application of foot pressure to said bar, circuit connections between said testing instrument and said testing contact members arranged so that upon application of foot pressure to said bar, said testing contact members will be brought into engagement with said rail and cause rail return current to produce on said instrument an indication of the resistance of a tested rail section between the intermediate testing contact member and one outer testing member in terms of the resistance of a standard rail section, a pair of auxiliary contact members disposed on said bar outside said outer testing contact members, an auxiliary current source associated with said apparatus, a normally open switch disposed on said bar so as to be closed upon application of foot pressure to a predetermined portion of said bar, and connections between said auxiliary contact members, said auxiliary source, and said switch, arranged so that upon application of foot pressure to said predetermined portion of said bar, said testing and auxiliary testing contact members will be brought into engagement with said rail and simultaneously said switch will be closed, causing a flow of current from said auxiliary source through said rail to produceon said instrument an indication of the V resistance of the tested rail section in the same terms as when actuating said instrument with rail return current. I

' FRANK W. ROLLER. 

